<html>
<body>
Checks for cases when you rewrite loop variable with inner loop
<pre style="font-family: monospace">
    for i in xrange(5):
      for i in xrange(20, 25):
          print("Inner", i)
      print("Outer", i)
  </pre>

It also warns you if variable declared in <code>with</code> statement is redeclared inside of statement body:
<pre style="font-family: monospace">
    with open("file") as f:
      f.read()
      with open("file") as f:
  </pre>
</body>
</html>
